The present invention relates to a filtering apparatus. More particularly this invention concerns a filter element for a disc-type filter apparatus.
A filtering apparatus is known having a housing defining a generally closed chamber to which is fed a filtrant fluid. A hollow shaft is rotatable in the chamber and carries a plurality of filter plates. Each of these plates is constituted as a metal plate and, spaced slightly from the plate, a filter cloth. The space between the filter cloth and the plate communicates via radial apertures with the interior of the hollow shaft which in turn is connected to the input of a pump. During filtering the pump, therefore, can pump the fluid through the cloth so as to filter from this filtrant fluid any particles, leaving them deposited on the cloth. Once a substantial filter cake has built up it is possible to rinse off the filter cloth by rotating the shaft while spraying against the cake on the cloth jets of water of the like. During such rinsing operation the sluicedaway filter cake may exit through a waste port at the bottom of the housing.
In all such installations there is provided between the metal filter-element plate and the cloth a screen or the like which serves to space this cloth from the plate so as to define an aspiration compartment. It is known to form the surface of the plate with corrugations or the like, but always there is provided a screen or perforated metal plate which lies underneath the filter cloth and prevents it from conforming in shape to the metal plate.
The provision of an extra support screen or the like increases the cost of the apparatus. Furthermore it increases the bulk of each of the filter elements so that fewer elements can be held in the same housing.
Various prior-art filters can be seen in Swiss Pat. Nos. 346,862 and 357,056 as well as in U.S. Pat. Nos. 2,687,217, 3,141,845, 3,142,642 and 3,033,373.